Color photography and cinematography



Nov. 22, 1938.

E. sANDERs-DoLGoRUKI ET A1. 2,137,785 COLOR PHOTOGRAPHY AND CINEMATOGRPHY Filed Oct. 2l, 1936 if 7' JAM/1671".

Patented Nov. 22, v1938 UNITED STATES COLOR PHUTOGRAIIY AND CINEMATOG- Edgar Sanders-D'olgoruki and John Hubert Reindorp, London, England, assignors to Truecolour Film Limited, London,

ish company Application g I England, a Britoctober 21, 1936, serial No. 106,881

n Great Britain October 9, 1936 Claims,

The present invention relates to a new or improved method oi obtaining differently colored images in two superposed emulsion layers or in two strata` of a single emulsion layer, and it is applicable both .to two-color subtractive records and to theproduction of two of the colors of a threeor four-color record. In German patent specification No. 632,925, a method. of obtaining two-color records is described in which the latent images in two superposed emulsion layers are iirst developed to silver and fixed, and then the silver image in the upper layer is converted by suitable treatment into silver iodide. The image in the lower layer' is converted into a Prussian blue image by treatment in a ferric solution, and the upper layer 4is colored by known dye-toning processes, the silver iodide in the upper layer acting as a mordant for the red dyestui. This process only permits the two specic colors mentioned to be obtained in the two layers, namely Prussian blue in the lower upper layer, and moreover there is the diiiiculty that the Prussian blue image in the lower layer would tend also to act as a mordant,so that there is a danger of dye being mordanted in this layer also, as well as in the upper layer.

The principal object of the present invention is to produce any desired colors in two superposed emulsion layers in a simple and satisfactory manner, and whereby the possibility of one layer being inadvertently colored during the coloringA of the other layer is almost Awholly eliminated.

In accordance with the present invention the method of producing differently colored images in two superposed emulsion layers consists in first developing silver in both layers, and then, after fixing, converting the image in the top-layer into silver iodide, and the image in the lower layer to silver ferrocyanide -or other salt capable of redevelopment,- and then redeveloping said lower layer with a color developer, after which the coloring of the upper layer is performed in any suitable manner.

There are several possible ways of coloring the upper layer; inasmuch as this layer contains a silver iodide image, it may be used lfor dye-toning by the application of basic dyestuffs, or the silver iodide image could be redeveloped to silver and a thin layer of a hot liquid solution ofa colloid 50 containing a transparent pigment or dye lake could be applied thereto, so that the surfaces of the silver image layer and the colloid layer become intimately interlocked, then the coated film could be treated in a solution containing a bleachlili4 ing agent to reduce the silver of the photographic layer, and red inthe v 0.4%, potassium iodide image, said bleaching agent containing a hardeningl agent capable of hardening the colored colloid layer adjacent the silver images, and then washing out the non-hardened parts of the colored colloid. i A still further method of obtaining the coloring in the top layer would be by colordevelopment byconverting the silver iodide image successively to silver and to silver ferro- `cyanide or other silver salt capable of redevelopment with a color-developer.

The single figure of the accompanying drawing comprises diagrams illustrating diagrammatically two methods of carrying the invention into effect, the diagrams representing diagrammaticallythe different stages in the formation of images in the two layers a and b after exposure.

In the methods illustrated, the rst step is the development of the latent images in the two layers to silver, and the removal by iixlng of the unaffected silver halide, as at A. The layers are `then treated in an aqueous solution containing iodine and potassium iodide; for example'. Iodine This solution penetrates through the emulsion layer a and whenthe image in this layerV has been converted into silver iodide, the time required for which operation must be determined by trial and error, the layers are removed .from the treatment bath, and are inserted in a stop bath containing sodium sulphite. This solution penetrates rapidly through the emulsion layers and arrests the action of the iodine-potassium .iodide solution. The result of this treatment is illustrated at B.

The next step in accordance with the present invention is the conversion of the image in the Ilower layer b into silver ferrocyanide. This may` be performed by placing the layers in a solution containing potassium ferricyanlde and ammonia,

for example thefollowing solution:

Potassium ferricyanide gm-- 20 Ammonia 28% solution; cc.. 20 Water q. sc cc 'rms step is iuustrated at C. In place of converting the image in the 'lower layer b into ferrocyanide,'it may be converted into any other silver salt which'is capable of redevelopmentwith a color-developer.

The material is now placed in a colordeveloping solution, the composition of which is dependent on the ,color which it is desired to produce in the layer b. Ii, for instance, the material is to be processed to form a colored negative according to co-pending United States application No.

1011,871 filed October 9, 1936, this layer is processed to magneta, and the following solution may be employed:

Diethylparaphenylenediamine hydrochlo- As a result of this treatment, the silver ferrocyanide image is developed to silver, and at the same time a magenta dyestuff is deposited therewith. The product of this step is illustrated at D.

Two possible ways of obtaining a colored image in the upper layer will now be described, one way being illustrated at Eand F, which is based on methods of dye-toning. In accordance with this method the material is inserted in a solution of a basic dye, which is capable ofbeing mordanted by a silver iodide image, and which produces a dyestufl image in the layer a, in accordance with the silver iodide image previously present in that layer. For example; if it is desired to produce a blue-green coloring in this layer the material may be inserted in an aqueous solution containing 0.5% iodine green, and 0.3% glacial acetic acid. The dycstuff in this layer may now be fixed with Silico-tungstic acid or phosphotungstic acid, for example. Finally, the silverin the lower layer, and the silver iodide in the upper layer may be removed by means of Farmer's reducer, leaving pure dye-images of the desired colors in the two layers a and b as illustrated at F.

Another way of forming the colored image in the upper layer is by the method described in British patent lspecification No. 377,706 as illustrated in the diagrams G to I. In accordance with this embodiment, the silver iodide image in the upper layer a is first redeveloped to silver in a suitable developer, for example an amidol-carbonate developer, such as the following:

Amidol gm 5 Sodium sulphite (crystals) gm 25 Sodium carbonate (crystals) gm 10 Potassium bromide gm 1 Water q. s cc-- 500 and is coated as shown at G with a warm solution of gelatine to form a layer c, this gelatine containing a transparent pigment or dye lake of the desired color. After the layer c has set, the material is inserted in a suitable bleach bath, such as one given in the aforesaid patent specification.

'I'his bleaches the silver image products capable of hardening the layer c in contact therewith. The material is now inserted in a bath of warm water at such temperature as to be capable of removing the unhardened parts of the gelatine layer c in contact therewith as shown at H. Finally, the silver in the lower layer b and the bleached silver salt image .in the layer a, are removed by a suitable reagent, such as Farmers reducer, leaving pure color images in or on the layers a and b, as shown in the diagram I. Y

The production of the image in the top layer may also be obtained by color development. For

and liberates parts of the example, the silver iodide image in the top layer may be developed to silver, for example in the amldol-carbonate developer given above, and then the silver image is converted into silver ferrocyanide by the controlled penetration of a ferricyanide bleach bath, such as that given above, but

containing a suitable proportion of a loading' agent or agents, such as glycerine and alcohol. The silver ferrocyanide image so formed may now be redeveloped with a color-forming developer.

In accordance with another method, the silver in the lower layer may be removed while the image in the upper layer is still in the state of silver iodide, by conversion into -silver ferrocyanide in the above mentioned ferricyanide bath for example, which has no effect on the silver iodide image in the upper layer. The silver ferrocyanide thus formed may be removed by means of sodium sulphite. The silver iodide image in the upper layer may then be dye-toned or converted successively into silver, and then into silver ferrocyanide as above described, and the latter redeveloped with a color-developer. This method avoids the necessity of using a loaded bleaching bath for converting the upper layer only to silver ferrocyanide.

The last mentioned modification, wherein the silver is removed from the lower layer, is advantageous moreover where the coloring of the top layer is obtained colored colloid layer as above described, and

vshown on the diagrams G, H, andI, since there is then no danger of the silver in the lower layer reacting with the bleaching and hardening bath and producing a hardening effect in the applied colloid layer additional to that produced by the silver in the upper layer.

The process has so far been described as applied to the coloring of two superposed emulsion layers, but it will be understood that these layers may be combined with other layers containing different color records as applied, for example, to a threeor four-color film. The two emulsion layers, thel processing o1' which has been described, may thus be mounted on one side of a suitable support of Celluloid or like transparent material, and on the other side thereof there may be located a third emulsion layer, the coloring of which may be performed by any suitable means, for example by color-development, dyetoning, or by the method of British patent specification No. 377,706. Of course the layers on the two sides of the support may be differently processed by flotation methods or a protective varnish layer may be provided on one side of the material to prevent the access of treating liquids thereto while processing the layer or layers on the other side of the support. Such a protective varnish layer when provided on the film during manufacture, may be arranged at the rear in the direction of the incident light, and may contain a neutral carbon black or a black dyestuilr so that this layer can act as an anti-halation backing where the material is used for making exposures in a camera.

In one method of carrying the invention into effect for the production of the three-color record by means of a photographic material having two emulsion layers on one side of a transparent support, and a third emulsion on the other side of the support, after exposure all the layers are first developed to silver and the material is fixed and washed. The outer emulsion layer of the side of the support carrying the two layers is converted into silver iodide in an iodine-potassium iodide solution such as that given above,

by the application of a' given above, and the` silver images namely the under layer on the same side of the' support, and the single layer on the other side of the support, are then converted into silver ferrocyanide in a erricyanide bleach bath as produced are successively color-developed to diierent colors 4in suitable color-developers, by .dotation processes or otherwise. The silver iodide image, already mentioned, is finally dye-toned to the desired color by the usual methods. Finally, the silver and the silver iodide in the layers are removed by means of Farmers reducer, for example.

In the case of a four-color film, two emulsion layers may be located on each side of a transparent support, and these layers may all be processed by the methods described herein.. Alternatively, two of the layers may be processed by the methods described herein while the remaining layers .are processed in any other suitable manner, for example as described in copending application No. 23110/36. i

Heretofore the invention has been described with reference to obtaining diil'erently -colored images in two superposed emulsion layers, but it must be understood that substantially the same methods may be adopted for the coloring of different strata of a single emulsion layer.

We claim:

1. A method of obtaining diierentl'y colored images in two photographic emulsion layers superimposed on one side of sists in developing silver images in both layers, iixing the layers, converting the image in the upper layer into silver iodide, and the image in the lower layer into a silver salt capable of redevelopment, redeveloping the image in the lower layer with a color developer, and coloring the upper layer in any suitable manner. h

2. A method of obtaining differently colored images in two photographic'emulsion layers superimposed on one` side of a support which consists in developing silver images in both layers, fixing the layers, converting the image in the upper layer into silver the lower layer into a silver salt capable vof redevelopment, redeveloping the image in the lower layer with a color developer and dyetoning the silver iodide image in the upper layer.

3. A method of obtaining differently colored images in two photographic emulsion layers Vsuperimposed on one side of a support which consists in' developing silver images in both layers, fixing the layers, converting the image in the upper layer into silver iodide and the image in the lower layer into a silver salt capable of redevelopment, redeveloping the image in the lower layer with a color developer, converting the silthe upper layer into silver,

layer, treating the assembly in a bleach hardening bath which reacts withthe silver image in the upper layer and liberates compounds which locally harden the parts of the colloid layer in contact with the silver image, washing outthe unhardened parts of the colloid layer and finally removing silver or silverlsalts from the layers to leave a colored colloid image in contact with the upperv layer.

4. A method of obtaining differently colored images in two photographic emulsion layers superimposed on one` side of a support which consists in developing silver images in both layers,

a support, which coniodide and the image inn fixing the layers, converting the image in the upper layer into silver iodide and the image in the lower layer into a silver salt capable of redevelopment, redeveloping the image in the lower layer with a color developer, converting the silver iodide image in the upper layer into silver, bleaching said silver image into a silver salt capable of redevelopment and developing the latter image with'a color developer.

5. A method of obtaining differently colored images in two photographic emulsion layers superimposed on one side of a support, after exposure of said layers which consists in developing silver images in both layers, fixing the layers, converting the image in the upper layer into silver iodide, and the image in the lower layer into' a redevelopable silver salt, color-developing the image in the lower layer, converting the silver iodide image in the upper layer into a silver image by means of an amidol carbonate developer, applying a colored colloid layer to said outer layer, treating all of said layers in a bleach hardening bath to locally harden the parts of the colloid layer in contact with the silver image in the upper layer, washing out the unhardened parts of the said colloid layer and removing silver or silver salts from all of said layers and leaving a hardened colloid image in contact with the aforesaid upper layer.

6. A method of obtaining ldifferently colored images in two photographic emulsionv layers superimposed on one side of a support, after exposure of said layers, which consists in developing silver images in both layers, fixing the layers, converting the image in the upper layer into silver iodide, and the image in the lower layer into a redevelopable silver salt, color-developing the ing silver images in both layers, xing the layers,

converting the image in the upper layer to silver iodide, converting the image in the lower layer into a redevelopable silver salt, color-developing the image in the lower layer, treating the layers in a ferricyanide bleach bath toconvert developed silver in the said lower layer into silver ferrocyanide, treating the layers in a solution ,of sulphite to remove said silver ierrocyanide, converting the silver iodide image in the upper layer intoX a silver image, applying a colored colloid layer to said upper layer, treating all of said layers in a bleach hardening bath to locally harden the parts ofthe colloid layer in contact with the 'silver image in the unhardened parts of the colloid layer, and rethe upper layer, washing out.

moving silver salts from said upper layer to leave superimposed on one side of a support, after exposure of said layers, which consists in developing silver images in both layers, xing the layers, converting the image inthe upper layer to silver iodide, converting the image the image in the lower layer, treating the layers in the lower layer .into a redevelopable silver salt, color-developing in a ferricyanide bleach bath to convert developed silver in the said lower layer into silver ferrocyanide, treating the layers in a solution oi' sulphite to remove said silver ferroeyanide, converting the silver iodide image in the upper layer to a silver image, converting said silver image into a redevelopable silver salt image, and developing said silver salt image in a color-forming developer.

image in the lower layer to silver ferrocyanide without ail'ecting the silver iodide image in the aii'ected, converting the silverv upper layer, redeveloping the silver ferrocyanide image in a color-forming developer and coloring the image in the upper layer in a suitable manner.

10. A method of obtaining diiierently colored images in two photographic emulsion layers superimposed on one side of a support, after EDGAR SANDERS-DOLGORUKI. 20

JOHN HUBERT REINDORP. 

